本文介绍了如何使用MongoDB计算每日平均字段?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我必须计算每天收集的平均费用.我每分钟创建一个查询.现在,我想将此查询转换为每天的平均值.我的每分钟查询情况如下
I have to calculate per day average of collection filed. I created one query on per minute basis. Now I want to convert this query in per day average.My per minute query as follows
db.voltage.aggregate(
{
$unwind: {
path:"$KeyValues",
includeArrayIndex:"arrayIndex",
preserveNullAndEmptyArrays:true
}
},
{
$project: {
timestamp:{
"$add":["$EventTS",{"$multiply":[60000,"$arrayIndex"]}]
} ,
"RVoltage":"$KeyValues.RVoltage",
arrayIndex:1,
}
},
{
$match: {
$and: [
{RVoltage: {$ne: null}}
]
}
}
);
您能建议我如何计算每天的平均值吗?
Can you suggest me how to calculate average per day?
推荐答案
按日期分组
db.voltage.aggregate([
{$project: {
date: {$dateToString: {format: "%Y-%m-%d", date: "$EventTS"}},
KeyValues:1
}},
{$unwind: '$KeyValues'},
{$project: {
date: 1,
RVoltage: '$KeyValues.RVoltage'
}},
{$group: {
_id: '$date',
avg: {$avg: '$RVoltage'}
}},
{$sort: {_id: 1}}
])
{ "_id" : "2015-07-02", "avg" : 234.1845454545454 }
{ "_id" : "2016-06-30", "avg" : 249.9316666666667 }
{ "_id" : "2016-07-01", "avg" : 244.08681818181822 }
这篇关于如何使用MongoDB计算每日平均字段?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!